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Development and validation of an integrated numerical tool for scaling control and squeeze treatment optimization (ARISSTON)

Objective

Objectives and problems to be solved :An old but persistent problem facing the oil industry is the formation of mineral scales from produced water/brines in oil/gas wells and pipelines. Lost production, formation damage and operational expenses caused by scale deposits cost hundreds of million US$ every year. The main objective of this project is the development and validation of an integrated numerical tool that can assist in the design and optimisation of a squeeze treatment for the prevention of scaling. The tool should predict the timing of scale deposition, the consequent formation damage distribution and the placement and flow of inhibitors in the near well formation. The validation of the tool involves both laboratory and field scales. Its application should reduce greatly the lost production and operational costs since it provides the chance for optimal design of the squeeze treatment (selection of inhibitor, inhibitor concentration, size of the pill, etc.) and for in-time placement of inhibitors at the zones where scaling is expected. Description of the work :The integrated numerical tool is to be built on a modular basis, with each module having an autonomous function, to facilitate testing, validation and upgrade. The tool consists of the following:
1. The main module, which is a single well, three-phase model simulating the fluid and heat flow in the well and the near-well formation.
2. The geochemical module for the simulation of chemical reactions.
3. The deposition/dissolution model for the computation of permeability and porosity alterations. The inhibitor flow model. Most of these numerical algorithms and their respective codes already exist, but they have to be tailored and integrated to the needs of the project. For the development and validation of the tool a series of scaling and squeeze experiments is planned. One of the innovative features of these experiments is the use of tracers, which is expected to give new information on the mechanisms of calcite and barium sulphate deposition and the inhibitor's action. A series of scaling tests in core plugs is planned using tracers to monitor scale deposition and providing unique information on the induction time and the distribution of scale deposition as function of pressure and temperature drop, absolute pressure and temperature, pH, salinity, saturation etc. This is followed by an experimental evaluation of the efficiency of a series of new, environmentally friendly inhibitors to prevent scaling. Measurements of the inhibitors' properties (adsorption isotherms, solubility, dissolution rates), necessary for the design of a squeeze treatment and as input to the numerical model, will be included. Finally an experimental evaluation of the new inhibitors' environmental friendliness will be performed. Expected results and Exploitation Plans: The deliverables of the proposed project include:
1. The validation of the use of tracer technology in scaling and squeeze experimental studies. This should lead to the development of improved laboratory procedures and maximize the potential for exploitation of such experimental information.
2. A deeper understanding of the mechanisms of scale precipitation and pore blocking in the near-well formations.
3.Experimental evaluation and selection of new, environmentally friendly inhibitors for the adequate prevention of scaling and a deeper understanding of the inhibitors' action.
4. Development and validation of an integrated numerical tool for the analysis and evaluation of scale precipitation/deposition, permeability reduction distribution around and along a well and the design of an inhibitor "squeeze" treatment both in vertical and horizontal wells. The impact is more pronounced in horizontal wells, where significant quantities of inhibitors are wasted with the traditional squeeze treatment methods due to the large length of the well and the unsymmetrical scale distribution.
The integrated numerical tool was built on a modular basis, with each module having an autonomous function, to facilitate testing, validation and upgrade. The tool consists of the following: (a) The main module, which is a single well, three-phase model simulating the fluid and heat flow in the well and the near-well formation. (b) The geochemical module for the simulation of chemical reactions. (c) The deposition/dissolution model for the computation of permeability and porosity alterations, and (d) the inhibitor flow model. Several of these numerical algorithms and their respective codes already existed, but they had to be tailored and integrated to the needs of the project.

For the development and validation of the tool a series of scaling and squeeze experiments was performed. One of the innovative features of the respective testsis was the use of tracers, which generated novel information on the mechanisms of calcite and barium sulfate deposition and the inhibitor's action. A series of scaling tests in core plugs using tracers allowed to monitor scale deposition and providing unique information on the induction time and the distribution of scale deposition as function of pressure and temperature drop, absolute pressure and temperature, pH, salinity, saturation etc. This was followed by the experimental evaluation of the efficiency of a series of new, environmentally friendly inhibitors to prevent scaling.

Measurements of the inhibitors' properties (adsorption isotherms, solubility, dissolution rates), necessary for the design of a squeeze treatment and as input to the numerical model, were also included. With regard to the development and validation of the integrated numerical tool, the single well black oil injection/production model has been completed and tested successfully using field data provided by the industrial partners of the project. The module simulating the inhibitor flow has also been completed and tested against both laboratory and field data. The geochemical model simulating calcite scaling has been completed, tested against laboratory data and coupled to the main black oil simulator. All the above components were integrated to generate the ARISSTON tool, which was tested successfully against the field data provided by the industrial partners BP (Miller field) and Amerada Hess (Ivanhoe).

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NATIONAL CENTRE FOR SCIENTIFIC RESEARCH 'DEMOKRITOS'
Address
Aghia Paraskevi, Attikis
15310 Athens
Greece

Participants (5)

AMERADA HESS LIMITED
United Kingdom
Address
Grosvenor Plasce 33
SW1X 7HY London
BP EXPLORATION OPERATING COMPANY LTD.
United Kingdom
Address
Chertsey Road 252
TW16 7LN Sunbury-on-thames
DYNO OIL FIELD CHEMICALS
Norway
Address
Lillestrom Fabrikker, Svelleveien
2001 Lillestroem
INSTITUT DE PHYSIQUE DU GLOBE DE PARIS
France
Address
Place Jussieu 4 Tour 24
75252 Paris
INSTITUTE FOR ENERGY TECHNOLOGY
Norway
Address
18,Instituttveien 18
2027 Kjeller